Method and apparatus for filling containers



'Jan- 1969 c. F. CARTER METHOD AND APPARATUS FOR FILLING CONTAINERSFiled April 1, 1966 Sheet INVENTOR.

CLARENCE F. CARTER BY M,%M,WM0/m q ATTORNEYS Jan. 14, 1969 c, CAR ER A3,421,554

METHOD AND APPARATUS FOR FILLING CONTAINERS Sheet 2 of 2 Filed April 1,1966 VACUUM CONTAlNER 6 4 VIII 18 W INVENTOR.

n CLARENCE E CARTER BY 4194. DO,

ATTORNEYS United States Patent Int. Cl. B65b 31/02; B67c 3/16 8 ABSTRACTOF THE DISCLOSURE Method and apparatus for filling containers withpowdered material by reducing the pressure in the container andutilizing the pressure differential to displace the powder from a hopperinto the container. The container is evacuated through a port near thetop of the container. The hopper valve is opened briefly and then closedto allow the vacuum to build up in the container while the valve isclosed. After one or more filling shots, the rate at which air is drawnout of the container through the port 15 reduced, thereby causingmaterial on the screens over the port to be dislodged before beginninganother ser1es of filling shots. Also, the vacuum may be maintamed inthe container at a high lever for a brief interval in order to shrinkthe powder that was previously deposited 1n the container.

This invention relates to a method and apparatus for filling containerswith particulate material and, more particularly, to filling containersby means of a pressure differential between the hopper and thecontainer.

Nonporous containers, such as cans, bottles and drums may be filled inaccordance with conventional techniques by applying a vacuum to theinterior of the container and then allowing particulate material to flowfrom a hopper into the container in response to the pressuredifferential acting on the material in the hopper. Generally, a fillinghead 1s applied to the mouth of the container and a hopper n which theparticulate material is deposited commumcates with the container througha valve openin in the filling head. A fiuid passage in the filling headczmmunicates with the interior of the container. A vacuum pump exhaustsair from the container through the passage to create a vacuum in thecontainer. The resulting pressure diflierential draws particulatematerial through the valve opening and into the container. Usually acontainer is filled by repeatedly opening and closing the hopper valveto deposit an increment of material in the container while the valve isopen and to build the vacuum back up in the container while the valve isclosed. Although this apparatus operates satisfactorily for fillmgcontainers with most types of particulate material there is a tendencyfor the screens over the vacuum pas sage to become clogged while thecontainer is being filled with material that has a very fine particlesize. The vacuum pump continues to draw air out of the container as thefine particles pass from the hopper into the container and some of theparticles are drawn toward the vacuum passage by the air currents. Also,the fine particles of material that are deposited in the bottom of thecontainer may be so light that some of them are drawn toward the vacuumpassage by the air currents in the container. Over a period of time, acoating of particles may be deposited on the screen covering the vacuumpassage. This coating limits the level of vacuum that can be built up inthe container.

In order to overcome the tendency for fine particulate material to coatthe screens over the vacuum passage, it has been proposed to provide apair of Passages and to "ice reverse periodically the flow of air acrossthe screens during the filling cycle, as described in my earlier patent,No. 2,170,469. Although this screen clearing step overcomes the problemof coating the screens with most powdered materials, it has thedisadvantage of requiring a certain amount of time during the fillingcycle for circulating the air across the screens and thus the rate atwhich containers can be filled is relatively slow. Also, if theparticles previously deposited in the container are very small, they maybe stirred up by the air currents and render the screen clearing stepineffective.

Accordingly, it is an object of this invention to provide a method andapparatus for filling containers with fine, particulate material.

It is a further object of this invention to provide a method andapparatus for rapidly filling containers with fine, particulatematerial, by means of a pressure differential, without clogging thevacuum passages.

These objects are accomplished in accordance with a preferred embodimentof the invention by applying a vacuum to the interior of the containerand then briefly opening the material supply valve to allow material toflow from the hopper into the container. When the supply valve is open,the pressure in the container rises and when the valve is closed, thevacuum builds up to a predetermined level again in the container. Theportion of the filling cycle between the time when the supply valvefirst opens until it starts to open again is known as a shot. Thebuildup of the vacuum occurs as rapidly as possible in order to reduceto a minimum the filling time for the container. The periodic openingand closing of the supply valve in this manner, while continuallywithdrawing air from the container is repeated until the container ispartially filled. This may require one or more shots.

The supply valve is again opened and closed to allow a charge ofmaterial to pass into the container, but the rate of flow of air out ofthe container through the vacuum line is substantially decreased, sothat the vacuum builds up slowly in the container. Thus, the aircurrents are not strong enough to draw the particles against the screen.When the vacuum has reached a predetermined level, the rate of flow ofair is adjusted to maintain the vacuum in the container at thepredetermined level for a certain interval of time. The supply valve isagain opened for the next shot during which material flows from thehopper into the container and the cycle may be repeated, as necessary,until the container is filled.

The apparatus for carrying out this method includes a valve arrangementfor adjusting the rate of flow of air out of the container through thevacuum line in order to vary the rate of buildup of vacuum in thecontainer and to maintain the vacuum at a selected level for a selectedtime interval.

This preferred embodiment is illustrated in the accompanying drawings inwhich:

FIG. 1 is a schematic view of the apparatus of this invention;

FIG. 2 is a cross sectional view of a filling head and container;

FIG. 3 is a cross sectional view of the filling head along the line 33in FIG. 2;

FIG. 4 is a schematic view of the vacuum pump and valve for controllingthe air flow from the container; and

FIG. 5 is a graph showing the changes in pressure in a container whileit is being filled.

Referring to FIG. 1, a filling head 2 is applied to the mouth of acontainer 4. The container 4 is clamped between the filling head 2 and amovable platform 6. A hopper 8 on the filling head body 10 receivesparticulate material which is to be deposited in the container 4.

The filling head body 10 has a gasket 12 which cooperates with the mouthof the container 4 to form a seal between the container and the body 10.Particulate material flows from the hopper 8 into the container 4through a central passage 14 in the filling head body 10. A valve 16ismounted in the passage 14 to control the flow of material from thehopper 8. The valve 16 has a resilient sleeve 18 which is inflated byair under pressure to expand and close the passage 14. The constructionand operation of the air-operated valve 16 is described in my Patent No.2,687,145.

Arcuate recesses 20 are formed in the lower surface of the filling headbody around-the passage 14. The recesses are covered by screens 22 whichare secured in the filling head body 10. Passages 24 in the filling headbody 10 communicate between the recesses 20 and the periphery of thebody 10. The passages 24 are connected to conventional tubing 26, whichis shown schematically in FIGS. 1, 2 and 3, by a threaded fitting 28.Another passage in the body 10 supplies air to the inflatable valve 16.Air is supplied through tubing 32 which is connected with the passage 30by a conventional fitting 34 at the periphery of the body 10.

As shownin FIG. 1, air under pressure is supplied to the tubing 32 by apump 34 and the flow of air through the tubing 32 is controlled by avalve 70. A vacuum pump 38 is connected to the tubing 26 and the rate offlow of air through the tubing is controlled by a valve 40. Of course,the pumps 34 and 38 may be a single pump with the tubing 26 connected tothe vacuum side and the tubing 32 connected to the pressure side. Thevalve 40 is an adjustable valve that is operated by a control unit 42.

Referring to FIG. 4, the control unit 42 includes a fluid actuator 44and a flow control system 46. The valve 40 has an inlet conduit 48 andan outlet conduit 50 which are connected to the filling head 2 and thevacuum pump 38, respectively, by the tubing 26. A valve seat 52 isprovided in a partition 54 which separates the inlet and outletconduits. A valve element 56 is supported on the end of a valve stem 58which is mounted for reciprocating movement in a bearing 60. Theopposite end of the valve stem 58 is connected to a piston 62 in thefluid actuator 44. The position of the valve element 56 relative to theseat 52 controls the rate of flow of air out of the container 4.

The control system 46 supplies air or other fluid to the actuator 44 tocontrol the position of the piston 62. The control system 46 must becapable of moving the valve element 56 to a fully open position duringthe initial portion of the filling cycle. While the element 56 is beingheld open by the piston 62, the system 46 inflates the supplyvalve 16 atregular intervals for each shot during which material flows into thecontainer and then the vacuum builds up again. After a predeterminednumber of shots, the system 46 closes the valve 56 to reduce the rate offlow through the valve 40 and thereby reduce the rate at which thevacuum is built up in the container 4. The vacuum is maintained in thecontainer for a predetermined time interval before the supply valve isagain opened. Then the valve element is displaced to a fully openedposition to provide a higher flow rate through the valve 40 during thenext shot.

A suitable system for controlling the supply valve 16 and vacuum valve40 is shown in FIG. 4. Of course, other systems may be used forcontrolling these valves in the manner described above. The system 46includes fluid conduits 64 and 66 which connect the pump 34 withopposite sides of the piston 62. The tubing 32 that supplies air to theinflatable valve 16 is also connected to the pump 34. A timer 68controls the flow of air to the actuator 44 and to the valve 16. Thetimer is a conventional type of electrical timer that trips relays atpreset time intervals. The relays in the timer are connected withsolenoid operated valves for controlling flow through the conduits 64and 66 and the tub-ing 32.

A solenoid valve 70 is operated by the timer 68 to open and close thevalve 16 at predetermined intervals. A solenoid valve 72 in the conduit64 controls flow to one side of the piston for displacing the valveelement away from the seat 52. Another solenoid valve 74 in the conduit66 controls flow to the opposite side of the piston 62. The valve 72 and74 are three-way valves, which in one position allow air to escape fromthe valve when air is being supplied to the actuator 44 through theother valve. Thus, the unbalanced pressure in the actuator causes thepiston 62 to be displaced in the desired direction.

The timer 68 is adjusted to close the valve 40 after a selected numberof shots. This is accomplished by opening the valve 74 to supply air tothe actuator 44 and allowing air to escape from the conduit 64 throughthe valve 72. Preferably, the valve 40 is closed at the same time thatthe valve 16 is inflated by operating the valve 70. In order to changethe rate of build-up of vacuum in the container 4, a bypass conduit 76is provided. The bypass conduit has a throttle valve 78. which may beadjusted to control the rate of flow of air through the conduit 64 tothe actuator 44. Flow of air through the bypass conduit 76 is controlledby a solenoid valve 80. The timer 68 is set to open the valveimmediately after the piston 62 has moved to close the valve 40.

The pressure conditions in the container 4 while the container is beingfilled in accordance with this invention are shown graphically in FIG.5. At the point A on the graph, the valve 70 is open to inflate thesupply valve 16. The valve 72 is open to supply air to the actuator 44and the valve 74 exhausts air from the conduit 66. The valve 80 isclosed and the throttle valve 78 is adjusted to produce the desired rateof movement of the valve element 56. As the first shot starts, the valve70 is closed by the timer to open the supply valve 16 and allow powderedmaterial to flow from the hopper 8 into the container 4. Since theinterior of the container 4 is in communication with atmosphericpressure through the hopper 8, the vacuum in the container decreases asthe material flows into the container. At the point B on the curve, thesupply valve 16 is closed by means of the valve 70. The vacuum 40remains open after the valve 16 closes and the vacuum rises rapidly tothe point C on the curve. The first shot is then completed. A series ofshots similar to the first shot may be provided.

At the point C, the su ply valve 16 is again opened by closing the valve70, and the vacuum valve 40 remains open. The material flows from thehopper into the container as in the first shot. At the point marked D.on the curve, the supply valve 16 is closed by opening the valve 70 andthe vacuum valve 40 is closed by moving the element 56 against the valveseat 52. This is accomplished by means of the timer 68 which opens thevalve 74 and positions the valve 72 to exhaust air from the conduit 64.The pressure differential moves the piston 62 toward the valve seat 54until the valve 40 is closed.

Immediately after the valve closes, the control valve 72 is closed bythe timer 68 and the valve 74 is opened to the atmosphere. The valve 80is also opened to direct air through the valve 78 to displace theelement 56 away from the valve seat 52 at a sufliciently slow rate toprevent the powdered material in the container to be drawn up againstthe screens 22. The increase of vacuum in the container continues untilthe valve 40 is fully open, at about the point E on the curve in FIG. 5.Since the leakage of air into the container 4 is approximately constantwhen the supply valve 16 is closed, the level of vacuum in the containerremains approximately constant. The time interval during which thevacuum remains constant, the interval between points E and F, isdetermined by the timer 68. At the point P, the next shot starts.

The time interval required for carrying out the delayed vacuum buildupdepends primarily upon thesize of the container. A change in vacuum inthe container from 10 inches of mercury to 24 inches of mercury for afive gallon container may require five to ten seconds, while afifty-five gallon container may require up to fifty seconds.

This method produces better filling rates for fine materials, such assoft carbon black, paint pigments, light calcined magnesia, and aluminumpowders.

One of the advantages of this invention is that containers may be filledrapidly with light particulate materials by rneans of a vacuum, withoutcoating and clogging the vacuum outlet with particles of the materialbeing deposited in the container. Another advantage of the delayedvacuum buildup of this invention is that the material deposited in thebottom of the container by preceding shots tends to become compacted bythe gradually in-- creasing vacuum, so that a greater volume of materialmay be placed in the container.

While this invention has been illustrated and described in oneembodiment, it is recognized that variations and changes may be madetherein without departing from the invention as set forth in the claims.

I claim:

1. A method of filling containers with particulate material comprisingin sequence the steps of: withdrawing gas from the container at a firstpredetermined rate through a screened port to reduce the fluid pressurein the container, dispensing a quantity of the material into thecontainer through a valve from a zone at higher pressure, closing thevalve and withdrawing gas at a second predetermined rate from thecontainer through said port, said second rate being lower than saidfirst rate, whereby paricles of said material are dislodged from saidscreened port due to the lower rate of gas flow into said port duringsaid last mentioned gas withdrawing step.

2. The method of claim 1 including mairtaining said container at areduced substantially consant pressure for a predetermined time intervalduring said last mentioned gas withdrawing step.

3. The method of claim 1 wherein said first mentioned gas withdrawingstep and said dispensing step are repeated in sequence prior to saidlast mentioned gas reducing step.

4. Apparatus for filling containers with fine particulate materialcomprising a hopper, filling head means, seal means on said filling headmeans for receiving a container and forming a fluid seal therebetween,an air discharge port on said filling head means, said port having ascreen thereon, said filling head means including valve means forsupplying material from said hopper to said container, passage means forconducting air through said port from a container positioned inengagement with said sealing means, means for drawing air away from saidcontainer through said port at a first predetermined rate, and means forchanging the rate of flow of air through said port after a predeterminedtime interval.

5. The apparatus according to claim 4 wherein said flow rate changingmeans operates in phased relation with said supply valve means.

6. The apparatus according to claim 4 wherein said container issupported below said filling head means, whereby said material tends tofall toward the bottom of said container.

7. The apparatus according to claim 5 wherein said fiow raie changingmeans include-s a valve in said passage means, said valve having a firstposition and a second position, said valve first position providing airflow at said first predetermined rate and said valve second positionproviding air flow at a rate lower than said first predetermined rate,fluid means for displacing said valve from one of said posiions to theother, and timer means for operating said fluid means at predeterminedtime intervals, whereby said valve is initially in said first positionand after a predetermined time interval is displaced to said secondposition, and after a second time interval is displaced back to saidfirst position.

8. The apparatus according to claim 6, wherein said timer is operativelyconnected to said filling head valve means for coordinating opening andclosing of said filling head valve means with said flow rate valve.

References Cited UNITED STATES PATENTS 2,642,215 6/1953 Carter l41286 XHOUSTON S. BELL, JR., Primary Examiner.

US. Cl. X.R. l4l59, 102, 286

